As the financial world's bankruptcies and bailouts are measured out in billions, it is sobering to be reminded how potent small numbers can be.

More than 5,000 children die every day for want of safe drinking water and basic sanitation.

Zimbabwe's cholera epidemic, which has been exacerbated by a lack of clean water, has killed more than 560 people. But it has infected 12,500 others and now threatens the region. As blocked toilets force Zimbabweans to defecate in the open, accelerating the spread of disease, the Government declared a state of emergency yesterday and appealed for the world's help. Zimbabwe is not suffering alone. Across Africa, people are being denied not only clean water and sanitation but also their dignity.

Pump Aid, one of three charities chosen by The Times for this year's Christmas Appeal, brings clean water and sanitation to Africa. It trains Africans to build and maintain robust, cost-effective water pumps that it has designed itself. Already more than a million people in Malawi and Zimbabwe drink uncontaminated water as a result of the work of Pump Aid. It has now begun to explore how best to bring safe water and latrines to areas of Liberia where there is only one tap providing clean water to every 5,000 people. Pump Aid believes it can reach one million Liberians within five years.

But the benefits spread beyond hygiene and basic privacy. Liberated from the burden of fetching water from distant sources, children now have time to attend a full day at school. Villagers can not only drink clean water, they can also irrigate crops to earn an income. Pump Aid changes lives for the better. It is worthy of your generosity.